john is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the sy

Question

zimovet [89]

3 years ago

15

john is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the sy

stem equations that represents the problem.

Mathematics

1 answer:

Verdich [7] · Answer 1 · 2022-01-14T18:44:41+03:00

Verdich [7]3 years ago

3 0

Hello,

let's assume j the john's age, m the mary's age.

<span>"John is twice as old as mary"==>j=2*m
</span>
<span>"the sum of their ages is 21" ==>j+m=21

==>2*m+m=21
==>3m=21
==>m=7
and j=21-7=14

</span>